I just hit th9 last week, and the loot is actually pretty amazing, just gotta find the right spots. I would say do it mostly because its ineffective to stay around with full storages all the time, although it will be quicker to finish the th8 upgrades now, if your really into walls I'd definitely recommend heading to 9, and plus the walls and heroes at th9 take forever so you can basically take your time with the defenses.
